a. Field of Invention
The invention relates to aircraft telemetry and control systems suitable for use in an unmanned aerial system (UAS) and, more particularly, to an ADS-B architecture for use in both manned and unmanned aircraft that provides airborne or ground control station (GCS) pilots with enhanced ownship and traffic situational awareness.
b. Background of the Invention
The Federal Aviation Administration (FAA) promulgates both Visual flight Rules (VFR) and Instrument Flight Rules (IFR) for all manned aircraft. VFR regulations require a pilot to be able to see outside the cockpit, and to control the aircraft's attitude, navigate, and avoid obstacles and other aircraft. However, an airborne pilot's cockpit instrumentation offers very limited en-route and terminal surveillance to augment the pilot's situational awareness, and offers minimal information on surrounding traffic, nor any traffic alerts.
The dearth of situational information is even more pronounced for Unmanned Aerial Systems (UASs) such as drones, which have no onboard pilot to perform the see and avoid function. Currently, UASs can only fly domestically in our National Airspace System with a Certificates of Approval (COA) or Experimental Airworthiness Certificate issued by the FAA. The FAA will only issue these certificates if a qualified ground observer or qualified personnel in a manned chase aircraft can perform the See-And-Avoid (S&A) function.
The demand for UASs is proliferating among the military, civil government, and private sectors due to significant improvements in their capabilities and performance. UAS-related research and innovation is driving the creation of companies and jobs, and UAS innovation has dramatically reduced the cost of aerial surveillance for law enforcement agencies and private companies. However, the proliferation of UASs is causing challenges as well. Without a regulatory framework, a large number of UASs in U.S. airspace would endanger commercial airlines and private aircraft. The FAA has not yet established Federal Aviation Regulations (FARs) for UASs to fly routinely in U.S. airspace. However, the FAA has been charged with developing a comprehensive plan for the integration of private UASs into U.S. airspace by late 2015.
It is reasonable to assume that any new FAA rules will impose requirements similar to manned aircraft. The FAA is mandating every aircraft operating within its airspace, where a transponder is currently required, to be equipped with Automatic dependent surveillance-broadcast (ADS-B) Out by Jan. 1, 2020. ADS-B is the satellite-based successor to radar. ADS-B makes use of GPS technology to determine and share precise aircraft location information, and streams additional flight information to the cockpits of properly equipped aircraft. ADS-B is a more reliable system for detecting and avoiding both cooperative aircraft and, importantly, non-cooperative aircraft such as parachutists, balloons, and manned aircraft without radios or navigation aids. Indeed, proposed FAR rules have been discussed. Any new FAA rules for UASs will inevitably impose strict standards for UASs, and is very likely to require some form of ADS-B-based collision avoidance technology. Unfortunately, current ADS-B Out lacks enhanced visual acquisition of real time traffic. Conventional ADS-B Out schema only transmit the immediate aircraft's position and velocity information automatically and periodically (at least once every second) without flight crew or operator intervention. Only air traffic controllers currently have information on surrounding aircraft positions, and the UAS's GCS has no information on surrounding aircraft or threats. Moreover, conventional aerospace telemetry networks require the use of efficient domain-specific protocols at the transport, network, and routing layers to protect against temporary loss of telemetry. However, the existing GCS devices (conventional computers) and services are based on legacy protocols such as wireless radio frequency communications via serial asynchronous protocols that serves as a conduit to assure the necessary UAS pilot situational awareness. ADS-B is susceptible to temporary loss of telemetry between the GCS, and if ADS-B data were to be transmitted using serial asynchronous or TCP/IP protocol it would be highly susceptible to telemetry loss. The loss of telemetry can occur from various factors such as simple line of sight distance, interference, to atmospheric disturbances. These constraints make conventional ADS-B ill-suited for remote-piloted UASs were situational awareness and conflict situational awareness is extremely limited.
One solution is for every GCS to transmit their UAS coordinates to air traffic control and let them consolidate and analyze all their data, inclusive of all UASs under their command. United States Patent Application 20100066604 by Limbaugh et al. (Kutta Technologies, Inc.) published Mar. 18, 2010 shows an unmanned aerial system (UAS) position reporting system in which an air traffic control reporting system (ATC-RS) receives position data of a UAS from its ground control station (GCS) and communicates the position of the UAS to a civilian air traffic control center (ATC) or to a military command through an ADS-B signal or through a TIS-B signal through the ADS-B and TIS-B transceiver. The ATC-RS is adapted to display the position of the UAS in the airspace on a display screen. This solution is cumbersome inasmuch as it requires four separate data transmissions to avoid a collision, and it is highly prone to temporary loss of telemetry.
A better solution is to use a UAS's ADS-B Out transceiver as a “repeater” to transmit not just the immediate aircraft discretes, but also other priority aircraft and ADS-B IN traffic information in the ADS-B telemetered signal. This way the GCS has all the data in one downlink.
U.S. Pat. No. 6,064,335 to Eschenbach (Trimble) issued May 16, 2000 shows a GPS based ADS-B system in which any properly equipped aircraft can know the position and heading of all neighboring aircraft. Each aircraft utilize GPS technology to determine its position and heading, and these discretes are transmitted to other ADS-B equipped aircraft, as well as ground control. Each aircraft in the vicinity would receive the GPS squitter and track the position and progress of neighboring aircraft, thus implementing a GPS squitter Traffic Alert and Collision Avoidance System (TCAS). Despite suggesting the repeater concept, the Trimble collision avoidance system only uses it to give a manned aircraft a way of visually cross-checking air traffic alerts from squitter avionics with air traffic controller communications. The suggested system is not adapted for use in a UAS and does not disclose a turnkey communication network between air and GCS.
What is needed is an ADS-B system that is more fully adapted for both airborne pilots and UAS pilots to provide a more comprehensive and failsafe detection and warning system to avoid accidents. Otherwise, impending FAA regulations are expected to severely limit the range and conditions under which UASs can operate. Disclosed herein is a system and method for ADS-B adapted for UASs to give them a new capability—to periodically transmit the ownship three-dimensional position and airspeed, as well as that of other surrounding aircraft in the vicinity, to the GCS and to use an ADS-B functional redundancy via a secure UDP/IP network link that is impervious to temporary telemetry loss for increased UAS situational awareness in uncertain environments. The system may also be deployed in the cockpit of conventional aircraft for enhanced ownship and traffic situational awareness of the airborne pilot.